Magnetic disk comprising an aluminum alloy oxynitride underlayer and a diamond-like carbon overcoat

ABSTRACT

A magnetic disk is protected by a bilayer. The bilayer is formed as an adhesion enhancing underlayer and a protective diamond-like carbon (DLC) overlayer. The underlayer is formed of an aluminum or alloyed aluminum oxynitride, having the general formula AlO x N y  or Me z AlO x N y  where Me z  symbolizes Ti z , Si z  or Cr z  and where x, y and z can be varied within the formation process. By adjusting the values of x and y the adhesion underlayer contributes to such qualities of the protective bilayer as stress compensation, chemical and mechanical stability and low electrical conductivity. Various methods of forming the underlayer are provided, including reactive ion sputtering, plasma assisted chemical vapor deposition, pulsed laser deposition and plasma immersion ion implantation.

This is a Divisional Application of U.S. patent application Ser. No.11/655,025 filed on Jan. 18, 2007, now U.S. Pat. No. 7,782,569, which isherein incorporated by reference in its entirety and assigned to acommon assignee.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the fabrication of hard disk drives (HDD),particularly to a method of protecting a magnetic head and magneticdisks by use of a diamond-like carbon coating on an underlayer that alsoserves as a corrosion barrier.

2. Description of the Related Art

Reducing the head-to-disk spacing (fly height) between a magneticread/write head and the surface of a magnetic disk rotating beneath ithas been one of the major approaches in achieving ultra-high recordingdensity in a hard disk drive (HDD) storage system. For a commerciallyavailable HDD with 160 GBytes capacity, the fly height is on the orderof 10 nanometers (nm). Maintaining such a small spacing between arapidly spinning disk and a read/write head literally flying above it isdifficult and an occasional contact between the disk surface and thehead is unavoidable. Such contact, when it does occur, can lead todamage to the head and the disk and to the loss of recorded informationon the disk. To minimize the head and disk damage, a thin layer of DLC(diamond-like carbon) coating is applied to both the surface of the headand the surface of the disk. This DLC also serves to protect themagnetic materials in the head from corrosion by various elements withinthe environment. Given the importance of the role of the DLC, it isessential that it is hard, dense and very thin, the thinness beingrequired to satisfy the overall fly height requirement while not usingup any of the allotted spacing. Currently a DLC coating between 20-30angstroms is found in the prior art.

Conventionally, DLC coating thicknesses are greater than 50 Å and forthat thickness range, there is a high degree of internal stress, leadingto poor adhesion with the substrate materials of the head as well as toother substrates to which they may be bonded. Because of high internalstress and thermal stress, an underlayer is required. For example, inapplications of cutting edges and drilling tools, the DLC thickness isin the micron range, and the working temperature can go up to a fewhundreds degrees Celsius. Thus, the coefficient of thermo expansion(CTE) of the underlayer also plays an important role. For these reasons,in prior arts, Japanese Patents JP 2571957, JP2215522 and JP3195301 haveproposed Si, SiO_(x), SiC and SiN_(x) for this adhesion layer. Itoh etal. (U.S. Pat. No. 5,227,196) discloses a SiN_(x) underlayer on an oxidesubstrate beneath the DLC layer. Various other types of adhesion layersare also found in the prior arts. Ishiyama (US Patent Application2006/0063040) discloses a carbon-based protection layer of hydrogenatedcarbon nitride for better adhesion. Hwang et al. (US Patent Application2005/0045468) teaches a Si underlayer for a DLC. Hwang et al. (US PatentApplication 2002/0134672) discloses Si, Al₂O₃, SiO₂, or SiN_(x) as anunderlayer beneath a DLC layer. David et al. (U.S. Pat. No. 5,609,948)describes a SiC underlayer under a DLC layer.

In addition to this cited prior art, adhesion layers comprisingmaterials other than Si have also been utilized in other areas. Natsumeet al. (U.S. Pat. No. 7,091,541) discloses the oxynitride TiAlON for anunderlayer between a capacitor dielectric layer and an electrode. Fu etal. (U.S. Pat. No. 6,238,803) shows a TiO_(x)N_(y) barrier layer for anAl electrode. Johnson et al. (U.S. Pat. No. 4,952,904) describes a metaloxide underlayer between silicon nitride and platinum. Stevens (U.S.Pat. No. 5,070,036) shows metal oxynitride as one of various materialregions in a VLSI circuit. Gillery (U.S. Pat. No. 4,861,669) shows aTiO_(x)N_(y) dielectric film.

For magnetic heads, the underlayer should have at least the followingproperties:

1. Electrical isolation property. For magnetic heads, electricalisolation must be provided for the magnetic metal alloy layers, such asthose layers comprising a magnetoresistive read head based on the giantmagnetoresistance (GMR) effect, or those layers comprising a devicebased on the tunneling magnetoresistive (TMR) effect. Electrical shortcircuits between these layers and surrounding HDD components will damagethe head or similar device. For this reason, the protection layers,especially the underlayer, should be insulating or semi-insulating.However, due to the semiconductor properties of Si, the surface shuntingof a Si underlayer can introduce noise, such as the so-called popcornnoise, into the GMR or TMR reader.

2. Anti-corrosion property. DLC films, particularly those producedthrough the filtered cathodic vacuum arc (FCVA) process of the priorart, are often embedded with micro- or nano-particles. These particlescan result in pinholes and corrosion of the materials used in formingthe magnetically active layers, such as NiFe and NiCoFe. Theanti-corrosion property of the underlayer is therefore of crucialimportance to maintaining the performance integrity of the sensor.

3. Anti-wear property. With the total thickness of the underlayer andthe DLC layer being reduced to the sub-30 angstrom range, literallyevery atom counts for the protection. Thus, a better anti-wear propertyis expected if we can put more atoms in the limited film thickness. Itis therefore very important that the underlayer have both chemicalstability for corrosion protection and high hardness for tribologicaladvantage.

It is the purpose of the present invention to provide a new class ofmaterials as underlayers to replace the Si and related materialsdescribed in the prior art cited above and to provide the aboveproperties.

SUMMARY OF THE INVENTION

The first object of the present invention is to provide a thinprotective layer for a magnetic read/write head or a magnetic recordingmedium to protect them from adverse effects of inadvertent mutualcontact and to provide wear resistance between the head and the mediumsurface.

The second object of the present invention is to provide such aprotective layer formed as a bilayer, wherein an overlayer is primarilya protective layer and an underlayer is primarily an adhesion enhancinglayer and a corrosion protection layer.

The third object of the present invention is to provide such a bilayerwherein inherent high resistivity of the underlayer eliminates surfaceshunting, thereby reducing noise, such as popcorn noise, from theread/write head.

A fourth object of the present invention is to provide such a bilayerwherein the underlayer forms a strong and stable chemical bond with theoverlayer.

A fifth object of the present invention is to provide methods forforming a protective bilayer that satisfies all of the above objects.

The objects of this invention will be achieved by the use of a class ofmaterials, the aluminum oxynitrides and alloyed aluminum oxynitrides,exemplified by AlO_(x)N_(y), Ti_(z)AlO_(x)N_(y), Si_(z)AlO_(x)N_(y), orCr_(z)AlO_(x)N_(y) and more generally symbolized Me_(z)AlO_(x)N_(y)where Me signifies an alloying metal. When the AlO_(x)N_(y),Ti_(z)AlO_(x)N_(y), Si_(z)AlO_(x)N_(y), and Cr_(z)AlO_(x)N_(y) areformed as underlayers, they can be deposited on a read/write head or amagnetic disk by sputtering, plasma immersion ion implantation (PIII),plasma immersion ion implantation deposition (PIIID), plasma enhancedchemical vapor deposition (PECVD), reactive pulsed laser deposition(PLD), etc.

The aluminum oxynitrides and alloyed aluminum oxynitrides shown aboveare carbide forming compounds that exhibit good adhesion to DLC films.In addition, they have also been shown to have good adhesion tosubstrate materials used in magnetic read heads, such as AlTiC, Al₂O₃,NiFe and NiFeCo and to a variety of other materials extensively used inthe semiconductor industry, such as Ti, Cr and Ta and others of acomparable nature.

The aluminum oxynitrides are also very good materials in terms of theirstability, chemical inertness, and the tunability (by variation of theiroxygen and nitrogen contents) of physical and chemical properties suchas stress, refractive index, and density, etc. For example, the hardnessof AlO_(x)N_(y) can be tuned from 12 GPa (AlN) to more than 20 GPa(Al₂O₃). In the case of Al₂₃O₂₇N₅, it hardness is about 18 GPa. One ofthe most important functionalities of the protection films is corrosionresistance and, as compared to silicon or amorphous silicon, Al₂O₃ andAlN are more stable and corrosion resistant.

The introduction of titanium, silicon, and chromium into the Al—O—Nsystem (i.e. Ti_(z)AlO_(x)N_(y), Si_(z)AlO_(x)N_(y),Cr_(z)AlO_(x)N_(y)), can also provide extra hardness. For example thehardness of TiAlN can be 50% higher than AlN. In addition, theintroduction of titanium and chromium can also promote the bondingstrength with diamond like carbon layer through forming Ti—C or Cr—Cbonds and to promote the adhesion to DLC films. Ti, Cr, and Al have beenwidely used as bonding elements for diamond particles (U.S. Pat. No.6,915,796). In the meantime, due to the good adhesion of aluminum,titanium and chromium, these films have good adhesion to the substratematerials in a magnetic head, including AlTiC, Al₂O₃, NiFe, NiFeCo, etc.

The formation of strong Ti—C and Cr—C bonds will promote adhesion of anAlO_(x)N_(y) underlayer to a DLC overcoat by adding Ti or Cr componentsto AlO_(x)N_(y), in the meantime, metal components in the underlayerwill adhere to the substrate material in the slider or media, namely,AlTiC, Al₂O₃, NiFe, NiFeCo, etc.

The AlO_(x)N_(y), Ti_(z)AlO_(x)N_(y), Si_(z)AlO_(x)N_(y),Cr_(z)AlO_(x)N_(y) underlayer can be prepared by reactive sputtering ofmetal, metal oxide or metal nitride targets within an Ar/O₂/N₂atmosphere or treated by Ar/O₂ and/or Ar/N₂ plasmas generated viadifferent methods, such as ion beam plasma, capacitively coupled plasma(CCP), inductively coupled plasma (ICP), or electron cyclotron resonance(ECR) plasma.

Preferred embodiments describing methods and examples of depositing anAlO_(x)N_(y), Ti_(z)AlO_(x)N_(y), Si_(z)AlO_(x)N_(y), orCr_(x)AlO_(x)N_(y) underlayer will be given below and illustrated below.In each of these embodiments and examples a vacuum deposition chamberthat can be pumped down to <10⁻⁶ Torr base pressure will be utilized. Anion source powered by an automatically matched RF power supplier, suchas a source that generates an Ar+ beam, is focused onto the target. Thesputtered target is deposited through its plume on a substrate, whichcan be a magnetic disk or a read/write head, and which is in continuousrotation to achieve good uniformity of the deposition. Ar, O₂ and N₂gases are introduced into the chamber/ion source through gas lines.

Normally, oxygen is more reactive than nitrogen; in addition, oxygen gasis more easily decomposed into atoms than nitrogen gas. These facts arevery important in the control of the gas flow and atmosphere in thedeposition systems, in order to obtain appropriate composition ofAlO_(x)N_(y), Ti_(z)AlO_(x)N_(y), Si_(z)AlO_(x)N_(y), orCr_(z)AlO_(x)N_(y) films.

For reference and comparison purposes, FIG. 1 provides a convenientlisting of several relevant mechanical and electrical properties ofvarious materials that are used in the fabrication of a magneticread/write head.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features, and advantages of the present invention areunderstood within the context of the Description of the PreferredEmbodiment as set forth below. The Description of the PreferredEmbodiment is understood within the context of the accompanying figures,wherein:

FIG. 1 is a table listing several relevant properties of materials usedin forming the read/write head and its protective coatings.

FIGS. 2 a and 2 b are flow charts of the prior art method of forming aprotective bilayer (2 a) and the present method of forming theprotective bilayer (2 b).

FIG. 3 is a schematic illustration of a slider mounted read/write headof the type on which the protective bilayer of the present invention isto be formed. The slider flies above a rotating magnetic disk of thetype also protected by the bilayer of the present invention.

FIG. 4 is a schematic illustration of an apparatus for producingparticular preferred embodiments of the invention using reactive ionbeam sputtering.

FIG. 5 is a schematic illustration of an apparatus for producingparticular preferred embodiments of the invention using a scannedfocused ion beam.

FIG. 6 is a schematic illustration of an apparatus for producingparticular preferred embodiments of the invention using a pulsed ionbeam.

FIG. 7 is a schematic illustration of an apparatus for producing apreferred embodiment of the invention using a pulsed high energy laser.

FIG. 8 is a schematic illustration of an apparatus for producing apreferred embodiment of the invention using an ion beam to sputter inthe presence of a plasma.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Each of the preferred embodiments of the present invention teach amethod of fabricating a thin protective bilayer over a magneticread/write head or recording media wherein the protective bilayercomprises an adhesion enhancing underlayer formed as an aluminumoxynitride, AlO_(x)N_(y), Ti_(z)AlO_(x)N_(y), Si_(z)AlO_(x)N_(y),Cr_(z)AlO_(x)N_(y) (more generally Me_(z)AlO_(x)N_(y)), over which isformed a hard, protective diamond-like carbon (DLC) overlayer (alsoreferred to as an overcoat).

Amorphous Si (a-Si) is widely used as an underlayer in the magneticrecording industry to promote the adhesion of a DLC layer to thesubstrate of a magnetic read/write head. In the prior art, the coatingprocess begins with the cleaning of the head substrate using an Ar⁺ ionbeam. Following this cleaning process, an underlayer of amorphous Si isdeposited using ion-beam sputtering (IBD) and then a DLC overlayer isdeposited using ion-beam deposition (IBD), PECVD or ECR, morepreferably, filtered cathodic vacuum arc (FCVA).

The preferred embodiments of the present invention differ from the IBDdeposition of a-Si because a totally different class of materials, thealuminum oxynitrides, and alloyed aluminum oxynitrides are formed as theadhesion layer. In the preferred embodiments the underlayer is formed asa layer that is deposited by reactive ion sputtering, plasma enhancedchemical vapor deposition (PECVD), reactive pulsed laser deposition(PLD) and other methods to be described below.

Referring to FIG. 3 a, there is shown, in flow chart form, a sequence ofthree steps that produces the protective bilayer of the prior art.

1. Substrate pre-cleaning using an Ar⁺ ion beam or Ar/O₂ ion beam as anetching mechanism.

2. Deposition of an adhesion underlayer of amorphous silicon (a-Si)using reactive ion sputtering.

3. Deposition of a protective overlayer of DLC, using IBD, PECVD orFCVA.

Referring to FIG. 3 b, there is shown a sequence of three steps thatproduces the protective bilayer of the present invention.

1. Substrate pre-cleaning using an Ar⁺ ion beam or Ar/O₂ as an etchingmechanism.

2. Deposition of an adhesion underlayer of aluminum oxynitride usingreactive ion sputtering of an aluminum oxide or nitride target within anAr/O₂/N₂ atmosphere or by using plasma immersion ion implantation,plasma immersion ion implantation deposition, plasma enhanced chemicalvapor deposition, or reactive pulsed laser deposition.3. Deposition of a protective overlayer of DLC, using IBD, PECVD orFCVA.

The following embodiments of the present invention are all methods bywhich a protective layer can be formed on a magnetic read/write head ora magnetic recording media (eg. a disk) that will meet all the objectsof the invention set forth above. In all of the embodiments, theprotective layer is formed as a bilayer on the disk or on an appropriatesubstrate surface of the read/write head, such as an air-bearing layersurface (ABS) that has been cleaned by an appropriate method such as Ar⁺beam or Ar/O₂ ion beam etching. It is also understood that there ispreferably a plurality of read/write heads mounted on a holder andsimultaneously treated by the method.

FIG. 4 illustrates a magnetic head-disk interface (not drawn to scale),where a magnetic head slider (10) is mechanically attached to itssuspension (110). The slider is built on AlTiC substrate (120) with anincorporated shielded GMR or TMR reader and writer (150) and an Al₂O₃overcoat (170). The reader shield, the reader, and writer materials aremainly formed of magnetic materials comprising various alloys andcompounds of Ni—Fe—Co which are subject to corrosion when exposed toenvironmental conditions. The slider is coated with an underlayer (180)and DLC overcoat (190).

On the other hand, the magnetic disk (20) is built on a glass oraluminum substrate (210) on top of which is an underlayer (220) and amagnetic layer (230), The surfaces of the magnetic layer is protected bythe underlayer (280) and DLC overcoat (290) formed by the method of thepresent invention. To minimize the abrasion with the slider head, a lube(lubricant) layer (260) is applied on the magnetic disk. The presentinvention provides the underlayer for both the slider (180) and for themagnetic disk (280).

First Preferred Embodiment

Referring now to FIG. 5, there is shown a schematic perspective drawingof an apparatus within which the protective bilayer of the presentinvention can be formed on a magnetic read/write head or on the surfaceof a magnetic recording disk. In this first preferred embodiment, as anexample of the method of reactive ion sputtering, the adhesion enhancinglayer will be formed as a layer of AlO_(x)N_(y).

The first preferred embodiment of this invention uses a depositionchamber (10) in which a vacuum of less than approximately 10⁻⁶ Torr hasbeen formed by a turbo pump. This chamber is substantially a commonelement in all of the following embodiments. Into this chamber an ionbeam, such as an Ar⁺ beam (20) is injected and directed at a target ofAl₂O₃ (50). The beam is produced by a RF source (30) and accelerated byvoltages that range from approximately 300 V to 1200 V. Injection ports(40) allow the injection of O₂ and N₂ gases into the chamber (10) withflow rates between approximately 0 and 20 sccm, and different ratios forreactive deposition, depending upon the desired form of the AlO_(x)N_(y)underlayer, with x within the range of approximately 0 to 1.5 and ywithin the range of approximately 0 to 1. As noted above, the Ar⁺ beamis directed at a target of Al₂O₃ (50) and the sputtered atoms (60)impinge on the device being coated (70), which can consist of read/writeheads or magnetic disks, a plurality of which are mounted on a rotatableholder (80) that can be rotated for uniformity of the deposition. In allthe formations of embodiments one through seven an overall thickness ofthe underlayer that does not exceed 50 angstroms produces results thatmeet the objects of the invention. An underlayer thickness that is lessthan 20 angstroms is most preferable although adhesion layers less than50 angstroms in thickness will meet the objects of the invention.Subsequent to the deposition of the adhesion layer, a layer of DLC (notshown) is formed on the underlayer using the methods cited above toproduce a bonded bilayer that meets the objects of the invention.

In a second version of the same first embodiment, the apparatus of FIG.5 is used as above, but the target material (50) is AlN, the Al nitriderather than the Al oxide. The Ar⁺ beam (20) is injected using an RFsource and accelerating voltages between approximately 300 V and 1200 Vand the O₂ and N₂ gases are injected into the chamber (10) with flowrates between approximately 0 and 20 sccm, and different ratiosdepending upon the desired form of the AlO_(x)N_(y) underlayer, with xwithin the range of approximately 0 to 1.5 and y within the range ofapproximately 0 to 1. As the Ar⁺ beam strikes the target of AlN (50) theresulting sputtered Al and N atoms (60) impinge on the read/write headsor disks (70) in the presence of the injected O₂ and N₂ gases to producethe desired AlO_(x)N_(y) adhesion layer. A plurality of the read/writeheads or a magnetic disk are mounted on a rotatable holder (80) foruniformity of the deposition.

It is also noted that x and y can be varied as the deposition processproceeds to produce adhesion layers with compositions that are afunction of layer thickness. In all these formations an overallthickness of the layer that does not exceed 50 angstroms producesresults that meet the objects of the invention. A layer thickness thatis less than 20 angstroms is most preferable.

Subsequent to the formation of the underlayer, a DLC overlayer is formedon the underlayer using methods cited above.

Second Preferred Embodiment

The second preferred embodiment of this invention uses the apparatus ofFIG. 6, which is similar to that of FIG. 5 in that it comprises adeposition chamber (10) into which a reactive ion beam (20), such as anAr⁺ ion beam, can be injected and directed at an Al target (50), whileinjection ports (40) allow the injection of O₂ and N₂ gases with flowrates between approximately 0 and 20 sccm, and different ratios, inorder to form desired form of the AlO_(x)N_(y) underlayer with x withinthe range of approximately 0 to 1.5 and y within the range ofapproximately 0 to 1. In this embodiment, however, the reactive ion beamis a high energy scanning, focused Ar⁺ ion beam (25) that is directed ata target of Al (50) and the sputtered atoms (60) impinge on the targetread/write heads or a magnetic disk (70), which are mounted on arotatable holder (80) for uniformity of the deposition. To avoidpoisoning the target and to eliminate hysteresis effects associated withthe deposition, there is used a high energy scanning focused ion beam asdescribed by T. Nyberg et al. (US Patent Application 2004/0149566A1)which is incorporated by reference here in its entirety. It is alsonoted that x and y can be varied as the deposition process proceeds toproduce adhesion layers with compositions that are a function of layerthickness. In all these formations an overall thickness of the layerthat does not exceed 50 angstroms produces results that meet the objectsof the invention. A layer thickness that is less than 20 angstroms ismost preferable.

As a second example of the method of this embodiment, all of the abovedescribed conditions remain substantially identical, but a target (50)of Ti_(z)Al alloy (more generally Me_(z)Al where Me hereinaftersymbolizes an appropriate alloying metal) is provided for the focused,scanning reactive ion beam and the sputtering process thereby producesan underlayer of Ti_(z)AlO_(x)N_(y) on either a read/write head or amagnetic disk. The sputtering process is still produced by the method ofNyberg described above and incorporated herein. The oxygen and nitrogengases are introduced with different ratios, in order to form filmcomposition of Ti_(z)AlO_(x)N_(y) with x in the range of approximately 0to 1.5+2z, y in the range of approximately 0 to 1+z. and z in the rangeof approximately 0 to 10. The flow rates of the oxygen and nitrogengases are the same as given above. It is noted that the values of x, yand z can change with the layer thickness as the deposition isproceeding.

As a third example of the method of this embodiment, all of the abovedescribed conditions remain substantially identical, but a target (50)of Si_(z)Al alloy is provided for the focused, scanning reactive ionbeam and the sputtering process thereby produces an underlayer ofSi_(z)AlO_(x)N_(y) on either a read/write head or a magnetic disk. Thesputtering process is still produced by the method of Nyberg describedabove and incorporated herein. The oxygen and nitrogen gases areintroduced with different ratios, in order to form film composition ofSi_(z)AlO_(x)N_(y) with x in the range of approximately 0 to 1.5+2z, yis in the range of approximately 0 to 1+z. and z in the range ofapproximately 0 to 10. The flow rates of the oxygen and nitrogen gasesare the same as given above. It is noted that the values of x, y and zcan change with the layer thickness as the deposition is proceeding.

As a fourth example of the method of this embodiment, all of the abovedescribed conditions remain substantially identical, but a target (50)of Cr_(z)Al alloy is provided for the focused, scanning reactive ionbeam and the sputtering process thereby produces an underlayer ofCr_(z)AlO_(x)N_(y) on either a read/write head or a magnetic disk. Thesputtering process is still produced by the method of Nyberg describedabove and incorporated herein. The oxygen and nitrogen gases areintroduced with different ratios, in order to form film composition ofCr_(z)AlO_(x)N_(y) with x in the range of approximately 0 to 1.5+2z, yis in the range of approximately 0 to 1+z. and z in the range ofapproximately 0 to 10. The flow rates of the oxygen and nitrogen gasesare the same as given above. It is noted that the values of x, y and zcan change with the layer thickness as the deposition is proceeding.

Subsequent to the formation of the underlayer, a DLC overlayer is formedon the underlayer using methods cited above.

Third Preferred Embodiment

The third preferred embodiment of this invention uses the apparatus ofFIG. 7, which comprises a deposition chamber (10) into which a reactiveion beam, such as an Ar⁺ ion beam can be injected and directed at an Altarget (50) while injection ports (40) allow the injection of O₂ and N₂gases with flow rates between approximately 0 and 20 sccm, and differentratios, depending upon the desired form of the AlO_(x)N_(y) underlayer,with x within the range of approximately 0 to 1.5 and y within the rangeof approximately 0 to 1. In this embodiment, however, the ion beam (20)is a pulsed Ar⁺ ion source with high instantaneous power, that isdirected at a target of Al (50) and the sputtered atoms (60) impinge ofthe target read/write heads (70) or media, which are mounted on arotatable holder (80) for uniformity of the deposition. To avoidpoisoning the target and to eliminate hysteresis effects associated withthe deposition, there is used a high instantaneous power pulsed ionsource as described by V. Kousnetsov et al. (U.S. Pat. No. 6,296,742)which is incorporated by reference here in its entirety. It is alsonoted that x and y can be varied as the deposition process proceeds toproduce adhesion layers with compositions that are a function of layerthickness. In all these formations an overall thickness of the layerthat does not exceed 50 angstroms produces results that meet the objectsof the invention. A layer thickness that is less than 20 angstroms ismost preferable.

As a second example of the method of this embodiment, all of the abovedescribed conditions remain substantially identical, but a target (50)of Ti_(z)Al alloy (more generally, Me_(z)Al) is provided for the pulsedreactive ion beam and the sputtering process thereby produces anunderlayer of Ti_(z)AlO_(x)N_(y) on either a read/write head or amagnetic disk. The sputtering process is still produced by the method ofKousnetsov described above and incorporated herein. The oxygen andnitrogen gases are introduced with different ratios, in order to formfilm composition of Ti_(z)AlO_(x)N_(y) with x in the range ofapproximately 0 to 1.5+2z, y in the range of approximately 0 to 1+z. andz in the range of approximately 0 to 10. The flow rates of the oxygenand nitrogen gases are the same as given above. It is noted that thevalues of x, y and z can change with the layer thickness as thedeposition is proceeding.

As a third example of the method of this embodiment, all of the abovedescribed conditions remain substantially identical, but a target (50)of Si_(z)Al alloy is provided for the focused, scanning reactive ionbeam and the sputtering process thereby produces an underlayer ofSi_(z)AlO_(x)N_(y) on either a read/write head or a magnetic disk. Thesputtering process is still produced by the method of Kousnetsovdescribed above and incorporated herein. The oxygen and nitrogen gasesare introduced with different ratios, in order to form film compositionof Si_(z)AlO_(x)N_(y) with x is in the range of approximately 0 to1.5+2z, y in the range of approximately 0 to 1+z. and z in the range ofapproximately 0 to 10. The flow rates of the oxygen and nitrogen gasesare the same as given above. It is noted that the values of x, y and zcan change with the layer thickness as the deposition is proceeding.

As a fourth example of the method of this embodiment, all of the abovedescribed conditions remain substantially identical, but a target (50)of Cr_(z)Al alloy is provided for the pulsed reactive ion beam and thesputtering process thereby produces an underlayer of Cr_(z)AlO_(x)N_(y)on either a read/write head or a magnetic disk. The sputtering processis still produced by the method of Kousnetsov described above andincorporated herein The oxygen and nitrogen gases are introduced withdifferent ratios, in order to form film composition ofCr_(z)AlO_(x)N_(y) with x in the range of approximately 0 to 1.5+2z, yin the range of approximately 0 to 1+z. and z in the range ofapproximately 0 to 10. It is noted that the values of x, y and z canchange with the layer thickness as the deposition is proceeding.

Subsequent to the formation of the underlayer, a DLC overlayer is formedon the underlayer using methods cited above.

Fourth Preferred Embodiment

The fourth preferred embodiment of this invention uses the apparatus ofFIG. 8, which comprises a deposition chamber (10) into which a highenergy pulsed laser can direct a beam of high energy, pulsedelectromagnetic radiation (25) at an Al target (50) while injectionports (40) allow the injection of O₂ and N₂ gases with flow ratesbetween 0 and 20 sccm, and different ratios, x/y, depending upon thedesired form of the AlO_(x)N_(y) underlayer. In this embodiment, theelectromagnetic radiation can be produced by a high energy pulsed lasersuch as a CO₂ laser, an excimer laser, etc and the atoms ejected (60) bythe laser beam impinge of the target read/write heads or magnetic disks(70), which are mounted on a rotatable holder (80) for uniformity of thedeposition. Values of x within the range of approximately 0 to 1.5 and ywithin the range of approximately 0 to 1, have produced adhesion layersmeeting the objects of the invention. It is also noted that x and y canbe varied as the deposition process proceeds to produce adhesion layerswith compositions that are a function of layer thickness. In all theseformations an overall thickness of the layer that does not exceed 50angstroms produces results that meet the objects of the invention. Alayer thickness that is less than 20 angstroms is most preferable.

As a second example of the method of this embodiment, all of the abovedescribed conditions remain substantially identical, but a target (50)of Ti_(z)Al alloy (more generally, Me_(z)Al) is provided for the highenergy laser beam and the sputtering process thereby produces anunderlayer of Ti_(z)AlO_(x)N_(y) on either a read/write head or amagnetic disk. The oxygen and nitrogen gases are introduced withdifferent ratios, in order to form film composition ofTi_(z)AlO_(x)N_(y) with x in the range of approximately 0 to 1.5+2z, yis in the range of approximately 0 to 1+z. and z in the range ofapproximately 0 to 10. The flow rates of the oxygen and nitrogen gasesare the same as given above. It is noted that the values of x, y and zcan change with the layer thickness as the deposition is proceeding.

As a third example of the method of this embodiment, all of the abovedescribed conditions remain substantially identical, but a target (50)of Si_(z)Al alloy is provided for the high energy laser and thesputtering process thereby produces an underlayer of Si_(z)AlO_(x)N_(y)on either a read/write head or a magnetic disk. The oxygen and nitrogengases are introduced with different ratios, in order to form filmcomposition of Si_(z)AlO_(x)N_(y) with x in the range of approximately 0to 1.5+2z, y is in the range of approximately 0 to 1+z. and z in therange of approximately 0 to 10. The flow rates of the oxygen andnitrogen gases are the same as given above. It is noted that the valuesof x, y and z can change with the layer thickness as the deposition isproceeding.

As a fourth example of the method of this embodiment, all of the abovedescribed conditions remain substantially identical, but a target (50)of Cr_(z)Al alloy is provided for the high energy laser and thesputtering process thereby produces an underlayer of Cr_(z)AlO_(x)N_(y)on either a read/write head or a magnetic disk. The oxygen and nitrogengases are introduced with different ratios, in order to form filmcomposition of Cr_(z)AlO_(x)N_(y) with x in the range of approximately 0to 1.5+2z, y in the range of approximately 0 to 1+z. and z in the rangeof approximately 0 to 10. The flow rates of the oxygen and nitrogengases are the same as given above.

Subsequent to the formation of the underlayer, a DLC overlayer is formedon the underlayer using methods cited above.

Fifth Preferred Embodiment

Referring to FIG. 8, there is shown a schematic perspective drawing ofan apparatus within which there is carried out a two-step process offorming the protective bilayer on a magnetic read/write head in accordwith a fifth preferred embodiment.

The fifth preferred embodiment of this invention uses the depositionchamber of FIG. 8 (10) into which a reactive ion beam such as an Ar⁺beam (20) is injected. The beam is produced by a RF source (30) andaccelerated by voltages that range from 300 V to 1200 V. The beam (20)impinges on an Al target (50) or alloyed Al target (Ti_(z)Al, Si_(z)Al,Cr_(z)Al, or, more generally, Me_(z)Al) causing target atoms to besputtered onto a plurality of magnetic read/write heads or magneticdisks (70) mounted on a rotatable holder (80) for uniform deposition.

After deposition of the sputtered film on the read/write heads, the filmis then exposed to a plasma (90) of Ar/O₂/N₂ gases (Ar being used as thecarrier gas) that is injected into the chamber (10) with differentratios x/y, depending upon the desired form of the oxynitride. When Alis used as the target, values of x within the range of approximately 0to 1.5 and y within the range of approximately 0 to 1, have producedadhesion layers meeting the objects of the invention. It is also notedthat x and y can be varied as the deposition process proceeds to produceadhesion layers with compositions that are a function of layerthickness. In all these formations an overall thickness of the layerthat does not exceed 50 angstroms produces results that meet the objectsof the invention. A layer thickness that is less than 20 angstroms ismost preferable.

Subsequent to the formation of the underlayer, a DLC overlayer is formedon the underlayer using methods cited above.

Sixth Preferred Embodiment

The sixth preferred embodiment of this invention is substantially thesame as the fifth embodiment, except that the injection of the plasmaoccurs while the sputtered beam strikes the read/write heads or disks.The embodiment uses the deposition chamber (10) of FIG. 8 into which areactive ion beam such as an Ar⁺ beam (20) is injected. The beam isproduced by a RF source (30) and accelerated by voltages that range from300 V to 1200V. The beam (20) impinges on an Al target or an alloyedTi_(z)Al, Si_(z)Al or Cr_(z)Al (more generally Me_(z)Al) target (50)causing target atoms to be sputtered onto a plurality of magneticread/write heads or a magnetic disk mounted on a rotatable fixture foruniform deposition.

The deposition of the sputtered film on the read/write heads or themagnetic disk (70) is carried out in the presence of a plasma (90) of O₂and N₂ gases (Ar can be used as a carrier gas) that is formed within thechamber (10) with different ratios, depending upon the desired form ofthe oxynitride. When Al is used as the target, values of x within therange of approximately 0 to 1.5 and y within the range of approximately0 to 1, have produced adhesion layers meeting the objects of theinvention. It is also noted that x and y can be varied as the plasmaprocess proceeds to produce adhesion layers with compositions that are afunction of layer thickness. In all these formations an overallthickness of the layer that does not exceed 50 angstroms producesresults that meet the objects of the invention. A layer thickness thatis less than 20 angstroms is most preferable.

Subsequent to the formation of the underlayer, a DLC overlayer is formedon the underlayer using methods cited above.

Seventh Preferred Embodiment

The seventh preferred embodiment of this invention uses the depositionchamber (10) of FIG. 8, in which a vacuum of less than approximately10⁻⁶ Torr has been formed by a turbo pump. Into this chamber a reactiveion beam, such as an Ar⁺ beam (20) is injected and directed at a targetof Al or an alloyed Ti_(z)Al, Si_(z)Al or Cr_(z)Al (more generally,Me_(z)Al) target (50). The beam is produced by a RF source (30) andaccelerated by voltages that range from 300 V to 1200 V. The beam (20)impinges on target (50) to be sputtered onto a plurality of magneticread/write heads or magnetic disks (70) mounted on a rotatable fixturefor uniform deposition.

After deposition of the Al sputtered film or Ti_(z)Al, Si_(z)Al orCr_(z)Al (more generally Me_(z)Al) films on the read/write heads, thedeposited film is then sequentially exposed to a plasma (90) of Ar/O₂/N₂gases (100) (or sequentially exposed to a plasma (90) of Ar/O₂ gases andAr/N₂ gases (100)) with different durations of the exposure, dependingupon the desired form of the Me_(z)AlO_(x)N_(y) layer (i.e. plasmasurface treatment of the already deposited Me_(z)Al film). The plasmacan be generated and applied by the use of any of a number of methodsknown in the art, such as plasma formation by an ion beam, formation andapplication of a capacitively coupled plasma (CCP), formation of anelectron cyclotron resonance (ECR) plasma or formation and applicationof an inductively coupled plasma (ICP).

It is also noted that x and y can be varied as the deposition processproceeds to produce underlayers with compositions that are a function oflayer thickness. In all these formations an overall thickness of thelayer that does not exceed 50 angstroms produces results that meet theobjects of the invention. A layer thickness that is less than 20angstroms is most preferable.

Subsequent to the formation of the underlayer, a DLC overlayer is formedon the underlayer using methods cited above.

As is understood by a person skilled in the art, the preferredembodiments of the present invention are illustrative of the presentinvention rather than being limiting of the present invention. Revisionsand modifications may be made to methods, processes, materials,structures, and dimensions through which is formed a protective bilayer,including an aluminum oxynitride underlayer or an alloyed aluminumoxynitride layer, on a magnetic read/write head or on the surface of amagnetic disk, while still providing such a protective bilayer, formedin accord with the present invention as defined by the appended claims.

1. A surface-protected magnetic disk comprising: the magnetic disk; asurface-protecting bilayer formed on the disk, the bilayer comprising:an adhesion enhancing underlayer formed of an aluminum oxynitride,AlO_(x)N_(y), formed on said disk; and a DLC overlayer formed on saidunderlayer.
 2. The surface-protected magnetic disk of claim 1 wherein xis in the range between approximately 0 and 1.5 and y is in the rangebetween approximately 0 and
 1. 3. The surface-protected magnetic disk ofclaim 1 wherein said underlayer is formed to a thickness less thanapproximately 50 angstroms.
 4. The surface-protected magnetic disk ofclaim 1 wherein said underlayer is formed to a thickness less thanapproximately 20 angstroms.
 5. The surface-protected magnetic disk ofclaim 1 wherein x and y vary over the underlayer thickness.
 6. Thesurface-protected magnetic disk of claim 1 wherein the underlayer isformed by a process of reactive pulsed laser deposition, reactive ionsputtering, pulsed reactive ion sputtering or scanning focused reactiveion beam sputtering, either in the presence of oxygen and nitrogen gasesor oxygen and nitrogen plasmas.
 7. A surface-protected magnetic diskcomprising: the magnetic disk; a surface-protecting bilayer formed onthe disk, the bilayer comprising: an adhesion enhancing underlayerformed of an oxynitride of an aluminum alloy, Me_(z)AlO_(x)N_(y), on acleaned substrate surface of the head, where Me_(z) is an alloyingelement having relative atom percentage z; formed on said disk; and aDLC overlayer formed on said underlayer.
 8. The surface-protectedmagnetic disk of claim 7 wherein Me_(z) is Ti_(z) and x is in the rangebetween approximately 0 to 1.5+2z, and y is in the range betweenapproximately 0 to 1+z. and z is in the range between approximately 0 to10.
 9. The surface-protected magnetic disk of claim 7 wherein Me_(z) isSi_(z) and x is in the range between approximately 0 and 1.5+2z, y is inthe range between approximately 0 and 1+1.3z and z is in the rangebetween approximately 0 to
 10. 10. The surface-protected magnetic diskof claim 7 wherein Me, is Cr, and x is in the range betweenapproximately 0 to 1.5+2z, y is in the range between approximately 0 to1+1.3z and z is in the range between approximately 0 to
 10. 11. Thesurface-protected magnetic disk of claim 7 wherein said underlayer isformed to a thickness less than approximately 50 angstroms.
 12. Thesurface-protected magnetic disk of claim 7 wherein x, y and z vary overthe underlayer thickness.
 13. The surface-protected magnetic disk ofclaim 7 wherein the underlayer is formed by a process of reactive pulsedlaser deposition, reactive ion sputtering, pulsed reactive ionsputtering or scanning focused reactive ion beam sputtering, either inthe presence of oxygen and nitrogen gases or oxygen and nitrogenplasmas.